Machine for automatically producing pressure-shaped articles, more especially tapered bore rivets



Jan. 12, 1943. R. H. MUMFORD 2,308,096

MACHINE FOR AUTOMATICALLY PRODUCING PRESSURE-SHAPED ARTICLES, MORE ESPECIALLY TAPERED BORE RIVETS Filed Aug. 29, 1941 4 Sheets-Sheet l l //VVEN 70 e A 7' TO ENEYS 2 ,308,090 -SHAPED Jan; 12, 1943'. R. MUMFOIQD MACHINE FOR AUTOMATICALLY PRODUCING PRESSURE ARTICLES, MORE ESPECIALLY TAPERED BORE RIVETS Filed Aug. 29, 1941 v 4 Sheets-Sheet '2 5 Mum/ aga Jan. 12, 1943. R. H. MUMFORD 2,308,096

MACHINE FOR AUTOMATICALLY PRODUCING PRESSURE-SHAPED ARTICLES, MORE ESPECIALLY TAPERED BORE RIVETS Filed Aug. 29. 1941 4 Sheets-Sheet 5 av VENTOFQ R. H. MUMFORD 2,308,096 MACHINE FOR AUTOMATICALLY PRODUCING PRESSURE-SHAPED ARTICLES, MORE ESPECIALLY TAPERED BORE RIVETS Filed Aug. 29, 1941 4 Sheets-Sheet 4 2. /IVVE'NTdf Patented Jan. 12, 1943 'lvIACHINE FOR AUTOMATICALLY PRODUC- ING PRESSURE-SHAPED ARTICLES, MORE ESPECIALLY TAPERED BORE RIVET'S Roy HoraceMumford, Harrow Weald, England, "assignor to Aviation Developments .Limited, Welwyn Garden City, England, a joint stock I company of Great Britain Application August29, 1941, Serial No. 408,860 In Great-Britain June 24, 1940 1 Glaini.

This-invention is for improvements relating to machines for automaticallyproducing pressureshaped articles, more especially tapered bore rivets, by a succession of operations including feeding material, for example in the case of a tapered bore rivet, a tubular blank, into a mould member, deforming the material in the mould member by means of a shaping member cooperating therewith and for this purpose reciprocatable towards and away from the mould member, and ejecting the shaped article from th mould member which latter is moved in a series of steps from a first position at which the feeding operation is performed, to a second position at which the deforming operation is performed and thence to a third position at which the ejecting operation is performed.

The object of the invention is to provide certain improvements in machines of this description, which will hereinafter be referred to as machines of the character specified, which principally will facilitate the operation of ejecting the shaped article from the mould member at the said third position thereof and which, moreover, will make for efiicient and simple design of the machine, having regard more particularly to the requirements of mass production of the articles to be produced without sacrifice of accuracy in respect of the shape and finished dimensions thereof.

According to the invention, a machine of the character specified, more especially such a machine for the production of tapered bore rivets, is characterised in that the shaped article is ejected from the mould member by a member which in the deforming operation, functions as an anvil member and in the ejecting operation works as a plunger toforce the shaped article out of the mould member in a direction opposite that of introduction thereinto of the blank to form the article, the ejecting member being movable with the mould member in the stepwise movement thereof and being operative in time with said movement and with the movements of the shaping member so as, while serving as a stop to locate'the blank in the first (blank feeding) position of the mould member and as an anvil in the second (blank forming) position thereof, to operate as an ejecting member for the shaped article in the third (article ejecting) position of the mould member.

Further, according to the invention, the ejecting member is preferably operated, at least as regards its operative stroke, by a cam, thereby providing for a gradual and progressive ejecting movement of the rivet or othershaped article from its position in the mould member.

Further, according to the invention, the improved machine is preferably of a rotary construction, after the manner of a turret bed press, there being a number of mould members (at least three) disposed at angular intervals around the rotational'axis of a rotatable mould member carrier and there being an ejecting member in association with each mould member carried therewith in the mould member carrier and arranged to be operated in respect of the operative stroke of the ejecting member by a fixed cam mounted on a spindle, extending coaxially through a central bore in .the mould member carrier. In this event, a preferredarrangement is one in which a part of the cam remote from the top thereof .ora part of the surface of a shaft on which the cam is mounted and from which it projects at one side of the shaft, serves as an abutment for the ejecting member against which it immovably bears during the first (blank feeding) and second (blank deforming) operations of the machine, that is, in respect of any given mould member of the number thereof carried in the mould member carrier, when the mould member is at its first and second positions in the machine around the axis of the mould member carrier. As regards the inoperative or return stroke of the ejecting member, this may, if necessary, be assisted by some automatically acting means, for example spring means which are compressed during the operative stroke of the member and which, as the camwhich has performed this stroke recedes from the member, comes into operation to return the member to the initial position again. Alternatively, the arrangement may be one in which the memberis returned to the initial position by thrust from the incoming blank as this is fed into the mould member at the blank feeding position thereof.

With the above preferred construction, a preferable arrangement is one in which, while the blank is being fed into one mould member at the first (blank feeding) position of the mould members, another'is being. deformed: in. another mould member at the second (blankdeforming) position of the mould members, and at the same time a fully shaped article is being ejected from another mould member still-atthe third (article ejecting) position of the mould members. In this way,-a high output of the machine is ensured.

There'may be more than one mould member and associated ejecting member ineach angular section .of the mould member carrier and correspondingly morethanione shapingmember' operative at each deforming position of the carrier, in which case the output of the machine would, of course, be a multiple of that which it would be if there were only one mould member and associated ejecting member per angular section of the mould member carrier and correspondingly only one shaping member per deforming position there In order that the invention may be clearly understood and readily carried into effect a preferred construction is hereinafter more fully described with reference to the accompanying drawings.

In these drawings;

Fig. 1 is a front elevation of a press embodying the machine tool;

Fig. 2 is a side elevation of the press as seen from the left hand side of Fig. 1;

Fig. 3 is a front elevation of the machine tool on an enlarged scale;

Fig. 4 is a plan view of Fig. 3;

Fig. 5 is an end elevation as seen from the right hand side of Fig. 3; and

Fig. 6 is a section taken on the line X--X of Fig. 3.

Referring now to the said drawings, and in particular to Figs. 3 to 6 thereof, the machine is rotary and is designed for the production of headed tubular rivets from tubular blanks and especially such rivets having a taper bore to be made from drilled tubular blanks. The machine comprises a casing I having a cylindrical bore in which is located a cylindrical mould carrier 2.

- The casing I is closed off by means of end plates 3, 4 and is surmounted by a top piece 5. Access is had to the tool carrier 2 through out out portions 6 and l.

The mould carrier 2 has a plurality, in the example six, equidistantly spaced radially extended bores 8 in each of which is mounted a mould 9 of hard metal having a blank shaping part which in the example is a recess 80 of frustoconical form seen in axial cross-section. Each mould 9 has a bore extending over the greater part of its length which communicates with the recess [0 through a bore of smaller diameter in which slides a plunger H. The plunger II has an enlargement l2 which slides in the bore of larger diameter and an extension Is. A spring M is located between the enlargement l2 and the end of the bore which spring tends to move the plunger so that its end will be retracted and the recess iii left free for the introduction of a blank. The plunger Ii may have an axial bore therein as shown in the drawings.

The mould carrier 2 is rotatable about a spindle 15 made fast to the end wall 3 of the casing l and is made fast to a stub shaft It which extends through the end wall t and terminates in a ratchet wheel I! with which engages a spring pressed retaining pawl E8. The spindle l5 has portions cut therefrom to provide flat surfaces l9 and 29 over which travel the extensions iii of the plungers II. This arrangement is such that as an extension moves across the surface 19 its spring 14 takes effect and moves the plunger ii to retract its one end from the recess Ill and urge its extension 53 into engagement with the surface It] which acts as a negative cam. The

surface 20 initially acts as an abutment preventing further axial movement of the plunger ii and thereafter acts as a positive cam causing gradual and progressive movement of the plunger H against the action of its spring I l until the plunger H is fully extended at the end of the v surface 29 and the end of the plunger is substantially flush with the mouth of the recess I0. As the extensions move over the curved portion of the spindle E5 the plungers remain fully extended.

The part 5 surmounting the casing l has an extension 2| having a vertical bore in which slides a member 22. The member 22 at its lower end is recessed to provide a peripheral wall 23 and the base is recessed to receive a press tool 24 having a tapered or otherwise suitably shaped shaping portion or pin 25 adapted to shape the blank in cooperation with the recess It) and also to form the head of the rivet. Thus during the operating (inward) stroke, the pin 25 enters the bore in the blank and deforms it to the desired shape when it completely fills the recess Iii.

The sliding member 22 has a horizontal bore in which is located a rod 26 held fast therein by a pin 2'5. At one end the rod 26 carries a freely pivoted arm 28 having an extension or tooth 29 adapted to engage the ratchet wheel H. A spring at is provided extending between the free end of the arm 28 and a fixed part of the casing, which spring tends to urge the arm 28 towards the ratchet wheel I! so that its tooth 29 will engage the latter. This arrangement is such that asthe member 22 is moved up and down in the operation of the machine, the arm 28 will similarly move up and down and during its up stroke its tooth 29 will engage and advance the ratchet wheel H by one tooth. The arrangement is furthermore such that the arm 28 moves overfar so that there will be an amount of lost motion during which time the shaping pin 25 is lifted clear of the mould before the mould carrier is rotated consequent on the movement of the ratchet wheel.

The feeding of prepared blanks is facilitated by the provision of a plate 3| having a slot 32 through which the blanks are individually introduced into the recesses H) in the moulds 9.

The toothed arm 28 provides an intermittent drive of the ratchet wheel I! so that the mould carrier 2 is advanced step by step the amount of this movement being sufficient to remove the one mould from below the tool and advance the next mould into that position. As has been indicated the mould carrier 2 is moved in timed relation with the movement of the tool by means of the toothed arm 28. Apart from all else, movement of the mould carrier is prevented during the shaping operation by the peripheral wall 23 entering into the bore 8 in which the mould is located.

In the use of the machine a blank is introduced into the recess I ii in the mould in advance of the tool whilst the mould carrier 2 is stationary and during the shaping of the blank in the mould below the tool the blank being properly located in the shaping recess If! by the end of the plunger H. On completion of the pressure stroke of the tool on the mould therebelow, during which time the plunger of that mould serves as an anvil, the tool is retracted and the mould face 26 so that that plunger is moved axially and acting now as an ejector forces the shaped article out from the mould in a, direction opposite to that in which it as a blank was introduced into the mould. This sequence in operation is then repeated.

The drilled blanks to form the rivets or shaped articles may be fed to the blank feeding position or positions of the moulds of the machine by any convenient means for this purpose; for example, they may be fed to the said position or positions on a feed wire extending centrally along a surrounding feed tube for the blanks, the said feed tube bearing at its delivery end on the circumference of the mould carrier or disposed closely thereto and means provided whereby as a mould comes into register with the delivery end of the tube, a blank shall pass automatically out of the tube into the recess I in the mould.

With this arrangement, it is necessary to cut a slot in the wall of the tube at the delivery end thereof to enable the blank which has passed into the mould member and which will project slightly beyond the mouth of the recess II], t effect its passage out of the end of the tube laterally thereof during the movement of the mould carrier 2 from the blank feeding position to the blank deforming position.

In the event of the feed tube for the blanks being arranged to bear upon the circumference of the mould member carrier in the manner described above, it is desirable for the feed tube to be resiliently held against said circumference.

The moulds may be interchangeable in the carrier therefor with others of a different size or shape, according to the size and shape of the rivets to be produced, and the shaping members and, if necessary, ejecting members may also be interchangeable in the parts which carry them to suit again the size and shape of the rivets or the requirements otherwise of the particular rivet forming operation in hand.

The engagement as between the ejecting memher and the cam which operates it may, if desired, be effected through the intermediary of a ball or roller bearing or a like anti-friction hearing means carried, for example, on the ejecting member at the inner end thereof.

The machine hereinbefore more particularly described may be used with any convenient press having a stationary part on which the machine may be mounted, and a movable part having an appropriate stroke for moving the tool carrying slide 22. The machine is shown mounted on a suitable press in Figs. 1 and 2 wherein the press shown has an inclined stationary bed 33 on which the machine may be firmly bolted by means of bolts 34 located in the slots 35 in lateral extensions 35 of the casing l and retained by means of wing nuts 36. The bed 33 is supported by a base 3'! within which is mounted an electric motor 45 and about which is a super-structure 38 carrying a cross shaft 39 on the ends of which are mounted fly-wheels 49, 4|. Centrally the shaft 39 carries suitable eccentrics denoted as a whole by the reference numeral 42 which serves to reciprocate a thrust member 43 on the free end of which is a bifurcated member 44 the limbs of which are hooked or recessed to receive the rod 26 and impart the movement of the thrust member to the slide 22 and the operating mechanism of the machine. The electric motor 45 drives the cross shaft 39 and the fly-wheels 40, 4| through a change speed pulley driving device the driver member 46 of which is carried on an adjustable arm 41. The drive is taken from the driver member to a pulley 48 and thence by an endless belt 49 to a pulley 50 fast on the crosshaft or with one of thefly-wheels, the tension of the belt being varied as desired by adjusting the position of the arm 41.

Heretofore, it has been the practice to produce tapered bore rivets from drilled blanks with the aid of three cooperatin but separate pieces of apparatus, a mould member in which the blank is inserted by hand, a shaping member including a part in the form of a pin which enters and deforms the blank in position in the mould member when forced into it from one end of the blank and an anvil member against the reaction of which the deforming operation is performed, there being an annular recess in the face of the shaping member surrounding the base of the pin comprised therein, a complementary recess in the adjacent end of the mould member, and a frusto-conical recess in an anvil member as in the case of the preferred embodiment described above of the present invention. It has been a difficulty, however, in the use of apparatus of this description to remove the fully shaped rivet from the mould member, owing to the firm hold of the rivet therein, coupled with the fact that the end face area of the rivet at the tail end thereof is rendered very small by the chamfering of the end of the rivet and usually insufficient to enable the rivet to be driven out without damage to it. In the machine of the present invention, this difficulty is entirely avoided, for the entire area of the end of the rivet, including that of the chamfer, is firmly and evenly abutted by the adjacent end of the ejecting member, with consequent maximum distribution of the stresses of thrust therefrom and the ejecting member is gradually and progressively advanced in this operative stroke and therefore without impartation of impact to the rivet.

What I claim is:

A machine for shaping articles by pressure from blanks, including a tool reciprocatable into and out of engagement with a mould, at least three moulds each having therein a recess to receive a blank, a spring-urged normally retracted slidable member within each of said moulds, a rotatable mould carrier, a shaft on which said carrier is mounted, means for rotating said carrier intermittently about said shaft in timed relation with said tool to present the moulds one after another to the tool, a fiat surface formed in said shaft which first permits a slidable member to be retracted by its spring and then limits the movement of that slidable member during the introduction of a blank into the recess in the mould, a second flat surface formed in said shaft for limiting movement of a slidable member during the time its mould is presented to the tool, and for causing subsequent axial movement of that slidable member to eject the shaped article from its mould as it moves away from the tool, and means for causing the shaping tool in reciprocating towards and away from a mould to impart said stepwise rotation to the mould carrier through a ratchet and pawl such that the pawl overruns the ratchet sufficiently far on the working s roke that the shaping tool is removed from the mould prior to the mould carrier member being moved.

ROY HORACE MUMFORD. 

